With climate change, comes a threat less discussed—harmful algal blooms, or HABs. A 2015 research published in the Geophysical Research Letters, a journal brought out by the American Geophysical Union, contends that the warming of summer surface temperatures of lakes—between 1985 and 2009, this rose by 0.34oC per decade, thanks to global warming—will increase algal blooming by 20% over the next 100 years. Global warming gives algal blooms the right mix of conditions to thrive. Cyanobacteria species—that carry the popular misnomer, blue-green algae—proliferate in warm water. Algae prefer saline water—changing salinity of freshwater bodies, as climate-change related droughts become more common, would make lakes, etc, vulnerable to blooms. The US’s Environmental Protection Agency notes that toxic marine algae have been killing fish in freshwater lakes in southwestern and south central parts of the country since early 2000s.
Given how they are reliant on CO2 for their growth, increasing concentrations of the gas in air and sea water favours the growth of Cyanobacteria. Increased rainfall in certain areas because of climate change means greater nutrient run-off from the land into water-bodies. In a nutshell, a quiet invasion of our water bodies by algae and Cyanobacteria is underway. Several Cyanobacteria species, like Microscystin, secrete toxins that endanger aquatic life (human health as well when they spread in water sources used by humans) while dinoflagellates like Alexandrium and Karenia cause reddish-brown blooms that have a toxic or otherwise harmful effect.
Thus, monitoring and mapping algal bloom has become a priority for most nations whose water bodies are under threat. Satellite imagery can tell you about the spread of a bloom, but they won’t be able to tell you if the water they are in has turned toxic. That requires physical gathering of water samples to be tested in labs. Now, this poses problems of its own. Hydrologists looking to get water samples or a specimen from the bloom can only rely on boats, but chances are quite high of the bloom getting entangled with the propeller or rudder of a boat and stalling it.
This year, scientists at the US’s National Oceanic and Atmospheric Administration (NOAA) enlisted the help of a robot—the Environmental Sample Processor (or ESPniagara) to monitor Lake Erie, 18 feet under its surface. ESPniagara collects algae from the surrounding water and analyses it for microcystin, a liver toxin secreted by the eponymous Cyanobacterium. Tentacle-like plastic tubing for sample processing make up the lower half of the robot that looks like a trash can. Given the water pressure and current at such depths as the one in which it operate, ESPniagara has been given a 1,000 pound encasing that can withstand pressures typical of hurricanes. The robot filters algal cells from the lake water. It is the testing afterwards that is a true marvel of technology.
While regular testing would require a lab equipped with centrifuges, temperature-controlled water baths, freezers, etc, ESPniagara does this within an inch-and-a-half tall apparatus that carries out toxicity testing with protocol that have been drafted for precision. A dish detergent is used to break cyanobacterial cells open—the toxin is contained within cells—while in a lab that would have been done by a cell disruptor. The toxin is detected by antibodies—free antibodies that don’t bind to the toxin (which is essentially a protein) exhibit fluoroscence. So, the brighter the dots of samples arranged in a grid, the safer the water.
A built-in camera captures images of the test array and a data buoy at the surface that is linked to ESPniagara sends off these images to the Monterey Bay Aquarium Research Institute, roughly some 2,500 miles away. Once the researchers at Monterey Bay get the toxicity data, they juxtapose it with satellite images of the algal biomass and windspeed and current data to estimate how toxic the entire bloom is and predict where the toxins will end up. That helps to know if the bloom will contaminate water supply at a specific location or not.
